Gatecrash

Hydroform | Instant | | Target land becomes a 3/3 Elemental creature with flying until end of turn. It's still a land. | Howard Lyon

Nimbus Swimmer | Creature | Leviathan | Flying Nimbus Swimmer enters the battlefield with X +1/+1 counters on it. | Howard Lyon

Shambleshark | Creature | Shark Crab | Flash (You may cast this spell any time you could cast an instant.) Evolve (Whenever a creature enters the battlefield under your control, if that creature has greater power or toughness than this creature, put a +1/+1 counter on this creature.) | Wesley Burt

Simic Charm | Instant | | Choose one — • Target creature gets +3/+3 until end of turn. • Permanents you control gain hexproof until end of turn. • Return target creature to its owner's hand. | Zoltan Boros

Zameck Guildmage | Creature | Elf Wizard | {G}{U}: This turn, each creature you control enters the battlefield with an additional +1/+1 counter on it. {G}{U}, Remove a +1/+1 counter from a creature you control: Draw a card. | Chase Stone

Biomass Mutation | Instant | | Creatures you control have base power and toughness X/X until end of turn. | Dan Scott

Clan Defiance | Sorcery | | Choose one or more — • Clan Defiance deals X damage to target creature with flying. • Clan Defiance deals X damage to target creature without flying. • Clan Defiance deals X damage to target player or planeswalker. | Daarken

Ground Assault | Sorcery | | Ground Assault deals damage to target creature equal to the number of lands you control. | Karl Kopinski

Gruul Charm | Instant | | Choose one — • Creatures without flying can't block this turn. • Gain control of all permanents you own. • Gruul Charm deals 3 damage to each creature with flying. | Zoltan Boros

Signal the Clans | Instant | | Search your library for three creature cards and reveal them. If you reveal three cards with different names, choose one of them at random and put that card into your hand. Shuffle the rest into your library. | Dave Kendall

Skarrg Guildmage | Creature | Human Shaman | {R}{G}: Creatures you control gain trample until end of turn. {1}{R}{G}: Target land you control becomes a 4/4 Elemental creature until end of turn. It's still a land. | Aleksi Briclot

Burning-Tree Emissary | Creature | Human Shaman | When Burning-Tree Emissary enters the battlefield, add {R}{G}. | Izzy

Pit Fight | Instant | | Target creature you control fights another target creature. (Each deals damage equal to its power to the other.) | Matt Stewart